Social Amoebae and Their Genomes: On the Brink to True Multicellularity

Abstract

Amoebozoa are one of the main branches of eukaryotes with an independent evolutionary history of more than 1 billion years. The social amoebae within this clade are capable of organizing several thousand cells during their developmental cycle to form sophisticated multicellular structures. Recently, the genomes of a handful of these social amoebae have been sequenced. This wealth of genomic data enables the in-depth analysis of common and derived genomic features, and allows us to draw conclusions regarding the basic requirements of multicellularity within this clade. The genomes of social amoebae are relatively small, but have gene numbers comparable to those of true multicellular systems. Some factors required for multicellularity are readily identifiable in these genomes, but others remain elusive as genome sequences from closely related outgroups to social amoebae are not yet available. Besides genes, genome and gene organization seem to play a role in establishing multicellularity. In this chapter I summarize the data obtained from all currently known genomes of social amoebae with an emphasis on features related to multicellularity.